WASHINGTON (AP) -- Secretary of State Rex Tillerson's surprising diplomatic offer of unconditional talks with North Korea hinges on two big X factors: Does the North even want talks, and is President Donald Trump fully behind his top diplomat?

Tillerson's overture came two weeks after North Korea tested a missile that could potentially carry a nuclear warhead to the U.S. Eastern Seaboard - a capability it has strove for decades to master. Trump has vowed to stop the reclusive government from reaching its goal, using military force if necessary.

After months of pressure tactics and military threats, many via presidential tweet, the new U.S. posture appears to reflect the Trump administration's official policy of "maximum pressure and engagement." China, which has urged dialogue, and U.S. ally South Korea, which fears disruption to the Winter Olympics it hosts in February, both welcomed Tillerson's proposal.

"We are ready to talk anytime North Korea would like to talk. And we are ready to have the first meeting without preconditions," Tillerson said at the Atlantic Council think tank on Tuesday, adding that the North would need to pause its weapons testing. It has conducted more than 20 ballistic missile launches and one nuclear test explosion this year.

Trump has described North Korea as the nation's most pressing national security crisis. Over most of his tenure, he has focused on pressuring Kim Jong Un's authoritarian government to abandon its weapons of mass destruction pursuit, through economic restrictions and diplomatic isolation.

But Tillerson, who will address a U.N. Security Council meeting on North Korea Friday, also has progressively eased the threshold under which he says the U.S. could hold direct discussions with North Korea.

In March, he said the North first had given up its nuclear weapons. A month later he demanded "concrete steps" reducing its threat. Tillerson said this summer talks could happen after the North stopped missile tests. And on Tuesday, for the first time, he explicitly dropped the condition that North Korea at least agree that the goal of any conversations be the elimination of its nuclear arsenal.

North Korea hasn't yet responded to Tillerson, who called it "unrealistic" to expect North Korea to enter talks ready to relinquish a WMD program it invested so much in developing.

"Let's just meet and we can talk about the weather if you want to. We can talk about whether it's a square table or a round table if that's what you are excited about," Tillerson said. "But can we at least sit down and see each other face to face and then we can begin to lay out a map, a road map, of what we might be willing to work towards."

North Korea, which now describes its nuclear force as complete, isn't showing interest in dialogue. At least yet.

Last week, U.N. political chief Jeffrey Feltman made a rare visit to North Korea and met the nation's foreign minister - a member of the powerful Politburo. Feltman, a former U.S. diplomat, said senior North Korean officials told him "it was important to prevent war." He said he urged them "start talking about talks," a commitment he didn't get.

After a closed briefing by Feltman Tuesday, Sweden's deputy U.N. ambassador Carl Skau was supportive but skeptical about chances for an opening. "There's nothing that was said that left us less worried than we were before," Skau told The Associated Press.

Patrick Cronin, an Asia expert at the Center for a New American Security think tank, said the Trump administration "has played hardball in trying to convert pressure into diplomatic opportunity." But so far, North Korea hasn't been willing to engage. He said it's unclear if the North will want to negotiate as it nears deployment of a nuclear missile that could strike America.

Another question mark: Trump's support for Tillerson.

Tillerson emphasized Tuesday that Trump endorses his position.

But in October, Trump appeared to undercut Tillerson by saying Tillerson was "wasting his time" trying to negotiate with North Korea. Trump's tweet followed Tillerson's talk about Washington maintaining back-channel communications with Pyongyang.

And doubts about Trump's broader confidence in Tillerson have persisted since White House officials revealed a plan last month to replace Tillerson with CIA Director Mike Pompeo.

Without White House support, Tillerson's call for unconditional talks would fall flat, said Mark Fitzpatrick at the International Institute for Strategic Studies. "A skeptic might say that at least he wants to show the U.S. is trying diplomacy, so as to make any future military action more justifiable," Fitzpatrick said.